Axial flow turbomachine and blade thereof

Abstract

Provided is a blade for an axial flow turbomachine, including: a blade profile section; an endwall having a flow path wall surface disposed at least on a hub side of the blade profile section and adapted to demarcate a part of an annular flow path of a working fluid; and a fillet disposed at the boundary between the blade profile section and the flow path wall surface. The fillet is externally shaped so as to have an arc-shaped curved surface having a radius of R as viewed in a cross-section orthogonal to the flow path wall surface and the blade surface of the blade profile section. A narrow portion existing on the flow path wall surface is configured such that the distance d between the outer edge of a projection of the blade profile section onto the flow path wall surface and the outer edge of the flow path wall surface is smaller than the maximum value of the radius R of the fillet. The upper end of the fillet is positioned lower in the narrow portion than that in a region other than the narrow portion, and the lower end of the arc-shaped curved surface coincides with the flow path wall surface along the entire circumference of the blade profile section.

What is claimed is: 
     
       1. A blade for an axial flow turbomachine, the blade comprising:
 a blade profile section; 
 an endwall that has a flow path wall surface disposed at least on a hub side of the blade profile section having a tip side and the hub side, and demarcates a part of an annular flow path of a working fluid; and 
 a fillet that is disposed at the boundary between the blade profile section and the flow path wall surface along an entire circumference of the blade profile section, wherein 
 the fillet is externally shaped so as to have an arc-shaped curved surface having a radius of R as viewed in a cross-section orthogonal to the flow path wall surface and a blade surface of the blade profile section, 
 a narrow portion existing on the flow path wall surface is configured such that a distance d between an outer edge of a projection of the blade profile section onto the flow path wall surface and an outer edge of the flow path wall surface is smaller than a maximum value of the radius R of the fillet, and 
 when a height is taken in a blade length direction from the flow path wall surface, an upper end of the arc-shaped curved surface of the fillet in the narrow portion is disposed lower than a lowest part of an upper end of the arc-shaped curved surface of the fillet in a region other than the narrow portion, and the lower end of the arc-shaped curved surface coincides with the flow path wall surface along the entire circumference of the blade profile section including the narrow portion. 
 
     
     
       2. The blade for an axial flow turbomachine, according to  claim 1 , wherein
 the narrow portion exists at least on a back side of the blade profile section having the back side and a front side. 
 
     
     
       3. The blade for an axial flow turbomachine, according to  claim 1 , wherein
 the radius R of the fillet in the cross-section is constant along the entire circumference of the blade profile section. 
 
     
     
       4. The blade for an axial flow turbomachine, according to  claim 1 , wherein
 the radius R in the cross-section of the arc-shaped curved surface in the narrow portion is small compared with the radius R in the region other than the narrow portion. 
 
     
     
       5. The blade for an axial flow turbomachine, according to  claim 4 , wherein
 the radius R in the narrow portion is equal to the distance d. 
 
     
     
       6. An axial flow turbomachine comprising:
 a stator blade that is the blade according to  claim 1 ; and 
 a rotor blade that forms one down-stepped section together with the stator blade. 
 
     
     
       7. An axial flow turbomachine comprising:
 a rotor blade that is the blade according to  claim 1 ; and 
 a stator blade that forms one down-stepped section together with the rotor blade. 
 
     
     
       8. A blade for an axial flow turbomachine, the blade comprising:
 a blade profile section; 
 an endwall that has a flow path wall surface disposed at least on a hub side of the blade profile section having a tip side and the hub side, and demarcates a part of an annular flow path of a working fluid; and 
 a fillet that is disposed at the boundary between the blade profile section and the flow path wall surface along an entire circumference of the blade profile section, wherein 
 the fillet is externally shaped so as to have an arc-shaped curved surface having a radius of R as viewed in a cross-section orthogonal to the flow path wall surface and a blade surface of the blade profile section, 
 a narrow portion existing on the flow path wall surface is configured such that a distance d between an outer edge of a projection of the blade profile section onto the flow path wall surface and an outer edge of the flow path wall surface is smaller than a maximum value of the radius R of the fillet, and 
 when a height is taken in a blade length direction from the flow path wall surface, an upper end of the arc-shaped curved surface of the fillet in the narrow portion is disposed lower than whole of an upper end of the arc-shaped curved surface of the fillet in a region other than the narrow portion, and the lower end of the arc-shaped curved surface coincides with the flow path wall surface along the entire circumference of the blade profile section including the narrow portion. 
 
     
     
       9. The blade for an axial flow turbomachine, according to  claim 8 , wherein
 the narrow portion exists at least on a back side of the blade profile section having the back side and a front side. 
 
     
     
       10. The blade for an axial flow turbomachine, according to  claim 8 , wherein
 the radius R of the fillet in the cross-section is constant along the entire circumference of the blade profile section. 
 
     
     
       11. The blade for an axial flow turbomachine, according to  claim 8 , wherein
 the radius R in the cross-section of the arc-shaped curved surface in the narrow portion is small compared with the radius R in the region other than the narrow portion. 
 
     
     
       12. The blade for an axial flow turbomachine, according to  claim 11 , wherein
 the radius R in the narrow portion is equal to the distance d. 
 
     
     
       13. An axial flow turbomachine comprising:
 a stator blade that is the blade according to  claim 8 ; and 
 a rotor blade that forms one down-stepped section together with the stator blade. 
 
     
     
       14. An axial flow turbomachine comprising:
 a rotor blade that is the blade according to  claim 8 ; and 
 a stator blade that forms one down-stepped section together with the rotor blade.